which Borla muffler

You can get Dynomax Ultra Flows. They are straight through and would be a direct replacement.

http://dynomax.com/mufflers.php?muffler=ultraflowelded

You are absolutely right, just returned from E Town today and got edumicated :) Met the dude with the beautiful green 70 'Cuda 440 (was a Viper color) had a complete tti 3" exhaust and the Dynomax Ultras. He introduced us to the guy who built the car, and he told us you can now get them right from tti. Direct bolt in, no welding. Thanks for the link